1. Technical Field
The present invention relates to a liquid supply device, a liquid ejecting apparatus, and a liquid supply method.
2. Related Art
An ink jet printer (hereinafter, simply referred to as “printer”) is a known example of a liquid ejecting apparatus that ejects a liquid onto a target from a liquid ejecting head. In this printer, if an ink solvent evaporates from the nozzle of a recording head serving as a liquid ejecting head, an increase in ink viscosity, ink hardening, or dust sticking may occur. The increase in ink viscosity, ink hardening, or dust sticking may cause clogging in the nozzle. In addition, air bubbles may enter the recording head from the nozzle, and defective printing may be caused.
Accordingly, as described in JP-A-2004-90453, in order to suppress nozzle clogging or air bubble mixing, a known printer performs cleaning, so-called choke cleaning. During choke cleaning, in a state where the valve provided in an ink supply channel (liquid supply channel), through which ink is supplied from an ink cartridge serving as a liquid supply source to the recording head, is closed, suction is applied in the recording head from the nozzle forming surface of the recording head through the nozzle. After negative pressure is generated in the recording head by the suction force, and air bubbles in the recording head are caused to expand, the valve is opened, such that ink quickly flows into the recording head from the ink cartridge. In this way, hardened ink in the recording head or air bubbles are forcibly discharged from the nozzle.
In the printer described in JP-A-2004-90453, only one valve that opens and closes the ink supply channel connecting the ink cartridge and the recording head is provided in the ink supply channel. For this reason, during choke cleaning, if the valve is opened, ink flows into the recording head from the ink cartridge through the ink supply channel in an amount corresponding to the negative pressure applied to the ink supply channel through the nozzle of the recording head. Accordingly, in this printer, during choke cleaning, a large amount of ink is wastefully consumed. In addition, when a plurality of ink supply channels correspondingly extend from liquid supply sources and are connected in parallel to the recording head, the amount of ink consumption in the respective liquid supply sources varies due to a difference in channel resistance between the ink supply channels.